The IRS targeting of conservative groups is far broader than first reported, with nearly 500 organizations singled out for additional scrutiny, according to two lawmakers briefed by the agency.

IRS officials claimed on Friday that roughly 300 groups received additional scrutiny. Reps. Darrell Issa, R-Calif., and Jim Jordan, R-Ohio, said Tuesday that the number has actually risen to 471. Further, they said it is "unclear" whether Tea Party and other conservative groups are being targeted to this day.

The lawmakers disclosed the additional information in a letter Tuesday to Lois Lerner, the IRS official who first disclosed the inappropriate practice. They sent the letter as a highly anticipated watchdog report was released, finding "inappropriate" action at the IRS.

The Republican congressmen also revealed that the IRS itself determined their effort was biased against conservatives more than a year ago.

"The actions of the IRS are unconscionable and appalling," they wrote.

Given the advance knowledge of the program, Issa and Jordan voiced serious concerns about the honesty of top IRS officials and the lack of disciplinary action. The lawmakers said they've learned nobody has been disciplined and that one employee at the Cincinnati office where this program was supposedly started "received a promotion or 'career enhancement.'"

They also questioned why top officials never disclosed the targeting effort when the agency conducted an internal review and found, on May 3 of last year, "significant problems in the review process and a substantial bias against conservative groups."

They said "at no point" did Lerner or anyone else inform Congress of the findings. And they claimed it appeared Lerner "provided false or misleading information on four separate occasions" in 2012 on the program. They were referring to requests made last year to the IRS about its vetting of Tea Party groups. Lerner and other officials did not reveal the internal concern about the effort at the time, they said.

Lawmakers across Capitol Hill were voicing concerns about the IRS program Tuesday, as independent investigators prepared to release a more complete accounting of what they discovered at the IRS.

Attorney General Eric Holder said he's ordered the Justice Department to investigate the agency.

Senate Democratic Leader Harry Reid said what the agency did is "inexcusable," though he said the agency has also inappropriately targeted left-leaning groups in the past.

Issa and Jordan wrote their letter after receiving a briefing from IRS staff.

They claimed that the additional scrutiny from the IRS effectively placed Tea Party and other groups "in a state of purgatory where they often languished without action for periods as long as two years."

Separate documents have indicated the program started as early as 2010.